Liver and Metabolism 14 Pharmacokinetics 1 – Drug absorption

Question 1

what are the 6 rights of prescribing

Answer 1

Right patient
Right drug
Right route
Right dose
Right time
Right outcome

Question 2

what is pharmacokinetics

Answer 2

what the body does to the drug

Question 3

what is pharmacodynamics

Answer 3

what the drug does to the body

therapeutic effect

Question 4

what does pharmacokinetics do

Answer 4

Facilitates safe and effective use of medicines
Determines optimal dosage regimen (dose, route, dose interval, duration of treatment)
Predicts potential drug interactions

Question 5

what makes up pharmacokinetics

Answer 5

absorption - Drug transfer from its site of
administration to the systemic circulation (blood)
distribution
metabolism
excretion

Question 6

Factors that influence enteral absorption

Answer 6

Gastrointestinal (GI) motility
Absorptive area
GI blood flow
Drug particle size and formulation
Drug physicochemical properties
Drug binding

Question 7

routes of drug administration

Answer 7

oral
rectal
(sublingual
buccal)

Question 8

how does solubility effect enteral absorption

Answer 8

lipid soluble - non polarised eg NaCl
hydrophilic (polar) - ionised molecules (Na, K)
more lipid soluble - more absorption, more water soluble, less absorption

Question 9

how does pH affect absorption

Answer 9

acidic drugs better absorbed by acidic media (same for basic)
acidic better absorbed by stomach and basic by intestines
better excreted in opposite media (important for poisoning)

Question 10

routes of drug administration

Answer 10

parenteral (injection)
Topical
Transdermal 
Inhalational
Intrathecal

Question 11

what is ideal dosing

Answer 11

between minimum toxic concentration and minimum effective concentration

Question 12

pharmacokinetic concepts

Answer 12

Absorption
First-pass (pre-systemic metabolism)
Bioavailability
Bioequivalence 
Volume of distribution
Cytochrome P450 enzyme system
Half-life
Steady state
Clearance

Question 13

what is bioavailability

Answer 13

Fraction of the administered (oral) dose of a drug that reaches the systemic circulation.
20% OBA needs to be 5x IV dose
Oral AUC/IV AUC

Question 14

what is first pass (pre-systemic) metabolism

Answer 14

metabolism of the drug prior to reaching systemic circulation.
hepatic
smaller it is, the greater the BA

Question 15

what is bioequivalence

Answer 15

Two drugs are considered bioequivalent when there is no significant difference in the rate or extent of bioavailability at the same molar dose and under the same conditions
relevant for different formulas and batches